Vacuum tube



H. H. KNEMANN VACUUM TUBE Eiled Sept.4, 1923 lllllllllllllllllllll Sept. 13-, 1927.

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Sept. 13 1927.

' 1,642,210 H. H. KNEMANN VACUUM TUBE Filed Sept. 4. 1923 2 Sheets-Sheet 2 Parenteel segr. i3, l1.927.

UNITED As'rarns li .1`\'rle.NT OFFICE.

HERMANN animaron xNnuANN, or' MUNsrEa, GERMANY.

, 'vacunar TUBE.

Application led September 1923, Serial No. 660,814, and in Germany September 8,* 1922.

My invention refers to vacuum tubes or mercury vapor rectifiers and its particular object is an improvement upon the tubes or rectifiers hitherto used which allows of. using i such a tube as a high current relay for varying direct or alternating cucigrent, so as to obtain a predetermined characteristic.

Up till now, one h'as not succeeded in transferring the principle underlying thel electron tube of controlling an electro-ii flow by means of a grid potential upon the control and regulation of high currents. More.-A

over it has especia ly proved impossible to produce high current with the yaid of free e1ectrons.-

According to my invention, this problem.

that thefwhole behaves like an electron tube with a comparatively high content of gas.

According to the present invention, I overcome these difficulties by employing as controlling member a body capable of being kept cool. In practisingmy invention, I can for instance introduce into the current traversing the mercury rectilier a coiled iron tube adapted to be supplied with a coling liquid, this tube being disposed in such a manner that theicurrent is forced to pass through between the coils.y

It has now been ascertained that withv an arrangement such as described above, when the device is not working, little .dro s ofr mercury will 'settle on the cooling tu e by condensation, and, if subsequentl the tube is again supplied with current, t` ese -drops of mercury will cause disturbances. It.1s,

therefore, necessary to prevent such recipitation of mercury from arising. n T is can be eiected by supplying the'cooling tube instead of with a cooling iquid, with la current of hot air serving to maintain thetemperature of this-,controlling memberatapoint lying between the temperature at'which the tube is heated to red heat and the temperature of condensation of mercurl. Y

In the drawings aiiixed to t'is specificasuch current.

tion and forming part thereof several embodiments of my invention are illustrated diagrammatically by way of example.

In the drawings- Figure 1 is a diagram of a rectifier tube embodying my invention, and

Figure 2 is a system comprising a tube of the kind ,aforesaid in combination with means for regulating it.

Figures 3-14 are dia rams illustrating different characteristics o lthe current.

Referring first to Figure 1, Gr is a vacuum tube or vessel and/Q, is the negative mercury electrode, while Z is the ignition electrode vwhich serves for permanently heating part of the surface of the mercury. A is the main electrode. If a corres onding voltage issupplied to A, there resu ts a current between A and Q, which is forced to pass through between the windings of a correspondingtube S dis o/sed intermediate the electrodesland exten ing across the` tube G. The distance between the windin s of the coil S is chosen in the form of alternating current, and more especially. in the form of semieriodsof On the other han the control of direct current at higher intensities has proved to be practically im ossible. In

order now to be` able to contro also direct current I cause it to be interrupted periodically by means of an oscillation circuit which is connected in parallel to the mercury arc and controlling the otential of the gri to predetermine whet er and when the current shally again be vforme-d. The .same applies also to each individual oscillation period of the circuitconnected in parallel.

lIn consequence thereof, it tis possible by adjusting the` voltage to cause the current to be started sooner or later, in other words,

i By the compensatinginductivities or capacities the effects of the individual impulses are then caused to be adapted-to the form of the voltage curve to be amplified, for instance the current curve of the microphone. This lattenway of proceeding can therefore be characterized in such way that direct cur- '.rent is subdivided in a mercury arc rectifier by aid of yan oscillation circuit into indiviual main current impulses which are then regulated by imparting to the grid at the different moments a voltage which causes the current to be started sooneror later within the oscillation periods of the circuits,

thevduration of which is 'the same, in accordance with the predetermined voltage.

In `consequence thereof, I may for instance employ the arrangement shown diagram-v matically in Figure 2, where G is the vacuum vessel, while A is the anode, Q, the inercury cathode, H\the heating electrode, L-C

the oscillation circuit interrupting the current and influencing the potential of the grid S by aid of T2. A system of this kindv operates as fllows:-The alternating current i, 3) to be amplified accordingly impresses its voltage for the time being byI aid of T1r Fig. 2) lonto the controlling grid ,i S. ,.According, now, as the controlling p01 tentialv influenced by T1 and T2 allows the lines of force to pass from the anode to the cathode or prevents them from-doing so, the current will be started lat each oscillation y sooner or later or not at all. As soon, however,

as it has acquired a certain value,`it be- .50 comes independent of the control bythe grid and wouldthen continue flowing, unless ini `t'errupted by the oscillation circuit L-TC.

.- ticularly the capacity are adapted to the outf The elements of these circuits, andmore parput of the 'rela and are solcho'sen' thatfthe' energy oscillating in thel circuit suffices to interrupt the direct current with certainty. ec (Fig. 4) illustrates the variations of 'voltage at the condenser C, while '11 f5) represents -the direct current impulses formed, the eHect fof which isl brought by vcompensatingv inductances or capacities to the formof the curve/v (Fig. 6) which represents an amplification of fio. The dimensions.v of thecompensati'ng elements men#y tioned above should again be adapted to the output of the relay and quite especially to the` period of the oscillation circuit, in order to obtain a non-distorted image of the controlling voltage in the direct current circuit.

If instead of T,L an optionalor positively ,v

is inallows controlled variation of the volta e serted, the system described not on to throw in `and out direct current, ut also 'to regulate it at will. This involves the advantages that this regulation takes place absolutelyfree of the effects of inertia and does not require any resistances inserted in`the circuit. l v Instead of the back coupling between the grid andthe oscillation circuit as shown in Fig. 2, yI may as wellemploy a foreignl'control of the grid, provided 'that care be taken to cause the oscillation circuit and the grid potential to be in phase. v

The curve z'., (Fig. 6) shows that there exists a direct current component, the magnitude of which can be determined -in the following Wayg-If the curve l in Fig. 8 represents the current impulses created by the direct current during the rst semi-period of an oscillationV of the circuit and if est (Fig 7 represents the potential of the grid which must be obtainedy before the current can be started; if further em (Fig. 7) is the medium position of the grid potential @gy about whichflit varies during the single oscillations, then ,as long as the grid potential is below .est no current can pass through. As

from 'the case of total interruption, would be obtained in the case where the line e...l dev sceiids so far that the point of eg just'touches the line e (Fig. 9). In this case only the [two halves of the first semi-periods will passv through which, being modified by ther in ductances 'and capacities, result in a direct v,current component- It is/impossible to lgo still farther down` so that with regard to the separation of direct .and alternating ciirrent, the curve shown in Fign 6 is obtained.A Further essential advantages are obtained if the irst point ofy intersection 7 or the point of contact (Fig. 9) between eg and est is s'hiftedfartlier to the right (Fig. 11.), the time during which the current is allowed; to act being thereby further shortened. This can be accomplished technically by` giving v to the curve eg a distorted'form, such asis obtained 1f a sinusoidal lcurrent is caused to pass through an 'induction coil, the iron core 'of which is more'or, less saturated magnetil cally. For this purpose there is insert-ed in the line' saturated by/ the direct currentwhich passes from the battery B over theiva-riable resistn leading to the grid a choking coil T3, the iron core of which iis more or less produced in the choking coil as shown,-

ance W. According to whether more or less resist-anceis, insertedin thesa1d line, the

core will be more'or less saturated and ac-V cording to the degree of saturation the curve es will be more or less distorted. It is thus possible to shift the point of intersection from eg (now called ef) -with est further to t-he right, so that it now intersects the line est in the second half of the first semi-period,

land in the case of maximum saturation, just namely by changes of the resistance W (Fig. 14). For the same' purpose any arrangement enabling the'V intensity of the magnetizing current to the modified mayI be used. Accordingly a microphone may be inserted in place of the resistance W. w v

I wish it to be understood that I do not desire to be limited to the exact details of;

construction, nor 'to the exact arrangement of arts shown and` described, for obvious mo ications will occur to a person skilled in the art.'

I claim I 1. The method of operating a mercury vapour tube comprising forming in said tube a4 mercury vapour arc and maintaining a cur. rent of hot air in the path of said arc. 2. The method of operating a mercury vapour tube'comprising forming in said tube a mercury vapour arc, maintaining a currentV of hot air the path of said arc and peri- .current charging said grid through said inodically in constant succession interrupting the current formin said arc.

3. A vacuum tu comprising a pair of electrodes, means for striking al mercury vapor arc between said electrodes, means for maintaining a current of hot air in the path of said are and an oscillation circuit fory periodically interrupt-ing the current forming said arc.

4. A vacuum tube comprising a pair of electrodes, means for striking a mercury vapor arc between said electrodes, means `for maintaining a current of hot air in the path of said arc, an oscillation circuit for periodically interrupting the current forming said arc and means for varying the potential of said air currentmaintaining means so as to permanently throw the current in and out. v

5. A vacuum tube comprising a pair of electrodes, means for striking a mercury vapor arc between said electrodes, ,a tubular grid in the path of said arc, means for feeding saidgrid with hot air, an oscillation circuit, means for causing said circuit to periodicall'y interru t'the current forming said arc and means or'causing said .grid to control the passage of said current. f

6. The method of operating a. mercury vapour tube comprising forming a mercury vapour arc between the electrodes in said tube and causing a current of hot air toI pa'ss throu h one of saidelectrodes.

7 .acuum tube comprising a air of electrodes, a lgrid intermediatesai electrodes, means for striking a .mercury arc between said electrodes, an inductance, a partly magnetically saturated ironcore in said inductance, and means for sending the sinusoidal ductance.

In testimony whereof I aiiix my signature.

HERMANN HEINR. KNEMANN.` 

